Growing up, Ben Silbermann liked to collect things: stamps, insects, you name it. At Yale, he studied medicine and political science. After college, he got a job as a consultant in Washington, D.C. Not exactly prototypical start-up material, but today he's CEO of one of the world's top social networks, Pinterest, which he co-founded and is valued at a staggering $1.5 billion.

By Christine Lagorio as seen in Inc.com